Four-wheel steering mechanism for vehicles



Aug. 16; 1949. A, c. STOVER FOUR-WHEEL STEERING MECHANISM FOR \fIEHICLES 2 Sheets-Sheet l Filed April 1, 1946 1949- A. c. STQVER 2,479,421

FOUR-WHEEL STEERING MECHANISM FOR VEHICLES Filed April 1, 1946 2 Sheets-Sheet 2 Patented Aug. 16, 1949 FOUR -.WHEEL STEERING MECHANISM' FORlVEHICIiES Ancil- C. Stover, ;Vann-Wert, Dhimassignobto The Eisenhauer Manufacturing Company, ,7 Van Wert, Ohio, a copartnership Application-April 1, 1946; S'rial NoZ 658324 Claims. 1

This:invention relatesgenerally to motor ve-"- hiclesqandi refers more particularly to improvementsxin the front: end; constructions of motor vehicles.

In certain types 'of' heavy duty vehicles such, forexamplepas truclml and tractors; it is advantageous'tozdividertheiloadaat the front-end between .tWO 'rtandem; axle assemblies including groundengaging wheels. Itihas longbeen recognized that such-an arrangement would reduce the unit load on-the road surface and greatly im prove handling of heavy duty vehicles, .but the problems ofzproviding satisfactoryrsteering mech-' anism: for thei'tandem 'wheelsprevented manufacturers; from 1 taking advantage of these features. a

Itlis an objectzofathis invention to provide commercially.practicalisteering mechanism composed ofia relatively fewwsimple-parts capable of being readily assembledin operative relation to tan-. dernlyv arranged-wheels to simultaneously steer both'sets" of wheels from a common' control. I

Another object :ofthis invention is togreatly improve the stability of-the front end assembl'y' and prevent wandering ofzthe steering wheels; by providing a construction which assuresmaintaining' a1predetermined caster angle or'steering knuckle-ipivot'rakeregardless of load variations or torque reactionsaresultingwfrombrake application.

Still another feature of: this invention is to provide-steeringmechanism: for tandem wheels embodying :a geometrical :arrangement: which "enables-obtaininga relatively wide steering radius withoutappreciable scufling of the tires on vthe road? surface.

The foregoing as .well as other" objects "will be made more apparent as this description proceeds;

especially when consideredin connection with the accompanying drawings, wherein Figurel is a fragmentary: side elevationalview of .the front endportion of a vehicle;

Figure 2 use plam-viewof the construction shown in Figure 1; t

Figure 3 is a sectional view takensubstantially on the line 13--3 of Figure 2; a

Figure/l is (a sectional: view takencn the line 4--4 of Figure 1;.

Figure 5 is .a sectionalview taken on. the line 5--5 of Figure; 1; and.

Figure 6 is a fragmentary perspective view of. one of the steering knuckles.

Referring now more in detail to the drawings, it will-be noted that'th'e reference character I01 indicates generallftheiront end portion of a vehicle. havinga frame I l comprising side sills l 2 secured-in lateral: spacedrelationshipby means of 'crosssmembers l3; The frame Ll I is supported ona setloftfront axles-M and i5: extending trans-r verselymfcthe side :sills l2; beneath the latter and spaced from each: 7 other; longitudinally :of s the frame;

The 1 front axle; I 4' of :the set-is =connected:="to' the'frame by a pair :of semielliptical leaf springs l6 and the rear axle |5 is similarlyvconnectedto the frame by a pair of semi-elliptical leaf springs I'I. The pairs of-springs I B and Ilare'respectively secured intermediate their ends to the front and rear axles. M and Win a manner :tobe morerfully hereinafter: described; 1 Thai-front ends hof: the springs; I 6 are; pivotedvto the corresponding ends oft-ther' frame "l I: by means of pins :18; and the rear endsrof ethe springsrare; respectively pivoted tolthe side sills lziby: means 10f. pinsalS; The ads" jacent endsxofcthe springs; at opposite: sidesof theif-rame. are respectively:connected'together by load-equalizing mechanism indicated generally by theareference(:character .20; This mechanism comprises a pair. of :sprockets 2 ii and" a paircrofi. chains-Jill The-intermediate eportions of" the chainsirespectively. mesh with the :sprockets .2 I: and the extremities :of: :the chains are? equipped with links 232 a The -.linl s- 23 ofthe chain at' one side of, the frame arerespectively mivotally see cured to; the .adjacenttendstof' the springs l6" and". IT: at the samesside. ofzthe rframe; while the links of; the chain .atathe-oppositeside of the framei are. respectively pivotallyconnected'to the adja cent ends :ofthe other set of springs. Thus, the loads applied to l the front 1 end portionof: the vehicle; are moreror less "equally distributed 'bel-= tween thefront and rear. axle!assembliesf -ll A ground :engagingrwheel is supported'at each axle end; anda steering" knuckle 24 of the type shown linnFigurers ofl the drawings; is provided: for this 1 purpose'.'-;. In accordance .with conven-. tional practice, theisteering knuckles are respec tively-pivotally:connected to the axle endslbyua king pin 25, having its axis inclined with respect: to-lthe vertical .to provide :the desiredcaster angle oresteering knncklespivotrakera The importance of'maintaining the kingpinsiat-the' proper caster:

, angle :is well. .known inthis art, and" provision is made herein ior; accomplishing tthis result re--- gard1ess.-.;of-load1 variations tor torque reactions.

caused by .brake application.. In..,general,,;the-

caster angle .is maintained. by rotatably supp rt ing the suspensionlspringa on the axles, andbyi connecting the axles with a torque arm 26. In"

rod 3|, which telescopically engages the tube. The front end of the tube and the rear end of the rod 3| are formed with vertical bores and are respectively secured to yokes 32 and 34 by vertical pins 33 and 35 extending through the bores. Suflicient clearance is provided between the pins and bores in the yokes to prevent binding of the parts during spring deflection. The yokes 32 and 34 are respectively secured tothe front and rear axles by plates 35' and suitable shims (not shown).

may be inserted between the plates and yokes to vary the caster angle as required. It follows from the foregoing that both axles are held against rocking movement and that the caster angles of the king pins on the respective axles are maintained notwithstanding stresses resulting from variations in load, spring deflection or torque reaction caused by brake application.

In the present instance, the ground engaging wheels connected to the front axle and the ground engaging wheels connected to the rear axle may be turned simultaneously in the same direction by manipulating a common steering control 35. The control 36 forms a part of a conventional type of steering gearing mechanism comprising a, housing 31'for the gearing (not shown) and a steering arm 38 connected to the gearing by a shaft-38', For the purpose of illustratiomit will be assumed that the steering gear mechanism is supported on the left hand side of the vehicle frame between'the front and rear axles. The swinging or lower end of the steering arm 38' is respectively comiected to a pair of arms 39 and 49. The arm 39 is pivotally supported on the frame H in advance of the front axle I 4 by a'pin 4|, and the arm 40 is pivotally connected to the frame at the rear of the axle [5 by a pin 42. The axes of the pins 4! and 42 extend parallel to the axis of swingin movement of the steering arm and are spaced equal distances from the latter axis. It will also be observed from Figure 1 of the drawings that the distance between the axis of the pin 4| and the axis of the front axle I4 is approximately the same as the distance between the axis of the pin 42 and the axis of the rear axle l5. The arm 38 is connected to theswinging endportions of the arms 39 and 49 by a pair of links 43 and 44 respectively. The link 43' is pivotally connected to the steering arm 38 by the adjustable coupling 45 shown in Figure 5 of the drawings, and the adjacent end of the link 44 is pivotally connected to the steering arm 38 by a similar coupling. In actual practice, the same couplingarrangement may be employed to respectively pivotally connect the'outer ends of the links to the arms 39 and 40. I V V i The steering knuckles 24 for the ground engaging Wheels'at the left hand side of the frame are respectively connected to the swinging ends of the arms 39 and '40. Upon reference to Figure 2 of the drawings, it will be noted that substantially U-shaped brackets 46 and have the outer leg portions respectively connected to the lefthandsteering knuckles 24. The inner leg portions of the brackets 46 and 41 are, in turn,.re-

4 spectively connected to the swinging ends of the arms 39 and 49 by drag-links 48 and 49. The drag-links are respectively pivotally connected to both the arms and brackets by couplings 59' of the type shown in Figure 4 of the drawings.

The axis of drag link 48 is aligned with the center line of the fixed hanger l8 to approximate all conditions, and the axis of the drag link 49 is similarly aligned with fixed hanger l9. Thus, an approximate common center is secured for the are which either axle describes when moved vertically, together with its accompanying drag link. As a result of this arrangement, vertical deflection of either axle in relation to the main frame cannot impart steering motion, thus promoting stability.

It follows from the foregoing that rocking movement of the steering arm 38 by the steering gear mechanism 3? imparts turning moment to the left hand front and rear ground engaging wheels. This turning moment is transferred to the right hand wheels by connecting rods 5| and 52. One end of the rod 5| is suitably pivotally connected to the bracket 46, and the other end of the rod is pivotally connected to a bar 53 which, in turn, is secured to the steering knuckle 24 associated with the front right hand wheel. One end of the rod 52 is pivotally connected to the bracket 41 and the opposite end is pivotally connected to a bar 54 which is secured to the steering knuckle 24 for the right hand rear wheel. In practice, it may be preferred to turn the front ground engaging wheels throughout a greater angle or radius than the rear ground engaging wheels in order to reduce scufiing of the tires on the road surface. The geometry of the steering linkage shown in the drawings is predetermined to afford the above result. In detail, it will'be noted that this is accomplished through the greater turning moment of the front idler arm 39 as compared with the turning moment of the rear idler arm 40, resulting from the differential in spacing of the coupling 45 of the link 43 from the center line of steering gear sector shaft as 7 compared with the spacing of the coupling 45 of the link 44 from the center line of the steering gear sector shaft. This differential is modified by the spacings of the couplings 59 of the link 43 and 44 on idler arms 39 and 40.

What I claim as my invention is: 1 1; A front end construction for vehicles comprising a frame, a pair of axles extending transversely of the frame in tandem relationship and having steering knuckles at opposite ends thereof, a ground engaging wheel journalled on each knuckle, a pair of arms respectively pivotally supported on the frame at one side of the latter beyond the axles outwardly thereof and having their axes of pivotal movement spaced substantially equal distances from the axes of the respective axles, drag links respectively connecting the arms to the knuckles on the same side of the frame as the arms, steering mechanism including an arm supported at said one side of the frame intermediate the pair of arms for rocking movement, links respectively connecting the steering arm to said pair of arms, and means connecting the knuckles at opposite ends of each axle.

2. A front end construction for vehicles comprising a frame, a pair of axles extending transversely of the frame in tandem relationship and having steering knuckles at opposite ends thereof, a ground engaging wheel journalled in'each knuckle, a pair of arms respectively pivotally upported onzthe framexiat onewsideiofctheilatter beyondtthe axles outwardly thereofiand having thiein taxes :of: ipivctamnovement spaced nub-stamtially equal:v distances from the-axes lof the respectiva axles-rforirockingunovement; drag-links respectively connecting thesarmsxto the-knuckles onithe' sameside lof th'elframe as the arms; steer ingimechanism @includiri'g" an arm supported at said one-side of the-frame intermediate the pair of: arms forrrockin'g movement; means connecting the steering 'knu-ckles atopposite ends of 'the' axies, and meansconnecting the steering arm to said pair :iof arms and responsive-to rocking movement of the steering l arm tc turn thewvheels associated with the front-wheel throughout-a grea'terradius than the wheels on the rear axle."

3. A front end-construction for vehicles comprising a frame, a pairnf. axlessextending transversely of thefram'e in tandem relationship and having steeringzknueklesoppositesends'thereof, a ground engaging wheel journalled-on each knuckle, means respectively.- connecting the knuckles at opposite ends of the axles together, an arm *jour-nalled on one sidebf the frame'in ad'- vance 1 of: the "front axle --and=ccnnected to -the knuckle at the adjacent end of the front axle, a second-arm journalled-on=the said one-side'of the frame in rear-of the-rear'axle'and connected to -the knuckleat-the adjacent end of said rear axle, steering mechanismdncludingan arm journalled on the same side of the frame as the arms aforesaid and having itraxisspaced equal'distances from the axes ofthefirst and second arms, andmeans" connectingthe-"steering arm to the first and second arms.

4. A front end construction for vehicles comprising a frame, a pair of axles extendingtransversely of the frame in tandem relationship and having steering knuckles at opposite ends thereof, a ground engaging wheel journalled on each knuckle, means respectively connecting the steering knuckles at opposite ends of the axles, an arm pivoted at one side of the frame in advance of the front axle and connected to the steering knuckle at the adjacent end of the frontaxle, a second arm pivoted at the said one side of the frame in rear of the rear axle and having its axis of pivotal movement spaced from the axis of the rear axle a distance substantially equal to the space between the axis of pivotal movement of the first named arm and the axis of the front axle, means connecting the swinging end of the second arm to the steering knuckle at the adjacent end of the rear axle, steering mechanism including an arm journalled at the same side of the frame as said arms and having its axis of swinging movement spaced equal distances from the axes of pivotal movement of said arms, and means connecting the steering arm to the first and second arms.

5. A front end construction for vehicles comprising a frame, a pair of axles extending transversely of the frame in tandem relationship and having steering knuckles at opposite ends thereof, a ground engaging wheel journalled on each knuckle, means respectively connecting the knuckles at opposite ends of the axles together, an arm journalled on one side of the frame in advance of the front axle and connected to the knuckle at the adjacent end of the front axle, a second arm journalled on the said one side of the frame in rear of the rear axle and connected to the knuckle at the adjacent end of said rear axle, steering mechanism including an arm journalled onztlre'sameaside-iotctheframe asttheiarms aforesaid: andifliaving its axis, spaced equal:-..dise tances from the axes of the first and secondiarms; andapainiof linkswofsubstantially equal length having their inner ends respectively pivotallycom nected t'o thesteerin'g arm and having their outer ends respective ly'i connected to the :first and sec: ondiarmsc 6. A front end-construction for vehicles oom prising aframe, a pair c-f axlesextending transe versely of thaframe inltandem relationship and havingsteering knuckles :atopposite ends thereof,-'=a ground engaging wheel journalled on'eac'h knuckle;means-respectively connecting the steering -knncklesat: opposite ends of the axles, an arm 'pivotedat 'onei side of the frame-in advance of the frontaxieand connected to the steering knuckleat -the adjacen-t ended the front-axle, a secondfiarm pivoted :a'tthe'said one side of the frame in rears of therear axle and having its axis of: pivotal movement spaced from the axis of the rear axle a distance substantially equal to: the spac'e between the "axis of pivotal movement ;of the first named arm andtheaxis of thefront-axle; means connecting thevswinging end-o'f the second armrt-oflth'e" steering knuckle at the adjacent end of -the rear axle, steering mechanism'includin an arm=journalled alt-the same sideaiofthe frame asisaidnarms andnhaving its axis of: swinging mcvement' spaced equal distances from the axes of: pivotalun-ovementsiof said arms, and a pair of, links? of substantially equal length having their innen"v ends respectively 1 connected to the steering: arm at different distances from the axis of swinging movement of said arm and having their outer ends respectively pivotally connected to the first and second arms.

7. A front end construction for vehicles comprising a frame, a pair of axles extending transversely of the frame in tandem relationship and having steering knuckles at opposite ends thereof, a ground engaging wheel journalled on each knuckle, pairs of suspension springs respectively supported intermediate the ends thereof on the axles and having the outer ends respectively pivoted to the frame, a pair of arms respectively pivotally supported at one side of the frame between the axles and outer ends of the springs, drag links respectively connecting the swinging ends of the arms to the knuckles at the same side of the frame as the arms and having their axes respectively lying in planes including the axes of l the pivotal connections between the outer ends of the springs and frame, and steering mechanism operatively connected to both of said arms.

8. A front end construction for vehicles comprising a frame, a pair of axles extending transversely of the frame in tandem relationship and having steering knuckles at opposite ends thereof, a ground engaging wheel journalled on each knuckle, pairs of suspension springs respectively supported intermediate the ends thereof on the axles and having the outer ends respectively pivoted to the frame, an arm journalled on one side of the frame in advance of the front axle, a second arm pivoted on the said one side of the frame in rear of the rear axle and having its axis of swinging movement spaced from the rear axle a distance substantially equal to the distance between the axis of swinging movement of the first arm and the front axle, drag links respectivelj connecting the arms to the knuckles at the same side of the frame as the arms and having their axes respectively lying in planes including the pivotal connections between the outer ends of the springs and frame, and steering mechanism supported on the frame and operatively connected to said arms.

9. A front end construction for vehicles comprising a frame, a pair of axles extending transversely of the frame in tandem relationship and having steering knuckles at opposite ends thereof, a ground engaging wheel journalled on each knuckle, pairs of suspension springs respectively supported intermediate the ends thereof on the axles and having the outer ends respectively pivoted to the frame, an arm journalled on one side of the frame in advance of the front axle, a second arm pivoted at the said side of the frame in rear of the rear axle, drag links respectively connecting the swinging ends of the arms to the steering knuckles at the same side of the frame as the arms and having their respective axes lying in planes including the pivotal connections between the outer ends of the springs and frame, steering mechanism including an arm pivoted on the same side of the frame as the arms and having its axis spaced equal distances from the axes of said arms, and means connecting the steering arm to the first and second arms.

10. A front end construction for vehicles comprising a frame, a pair of axles extending transversely of the frame in tandem relationship and having steering knuckles at opposite ends thereof, a ground engaging wheel journalled on each knuckle, pairs of suspension springs respectively supported intermediate the ends thereof on the axles and having the outer ends respectively pivoted to the frame, an arm journalled on one side of the frame in advance of the front axle, a

second arm plvotedat the said side of the frame in rear of the rear axle, drag links respectively connecting the swinging ends of the arms to the steering knuckles at the same sides of the frame as the arms and having their respective axes 1ying in planes including the pivotal connections between the outer ends of the springs and frame, steering mechanism including an arm pivoted on the same side of the frame as the arms and having its axis spaced equal distances from the axes of said arms, and a pair of links having their inner ends respectively pivotally connected to the steering arm at different distances from the axis of swinging movement of said arm and having the outer ends respectively conected to the first and second arms.

ANClL C. STOVER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,660,189 Fageol Feb. 21, 1928 1,815,416 Marcum July 21, 1931 1,933,674 Marcum Nov. 7, 1933 1,947,787 MacPherson Feb. 20, 1934 2,323,669 Murty et al July 6, 1943 FOREIGN PATENTS Number Country Date 312,475 Great Britain May 30, 1929 336,666 Great Britain Oct. 20, 1930 

